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Update 10-classical-sorting-algorithms.md

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docs/cs-basics/algorithms/10-classical-sorting-algorithms.md
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@ -77,7 +77,7 @@ tag:
* @param arr * @param arr
* @return arr * @return arr
*/ */
public static int[] BubbleSort(int[] arr) { public static int[] bubbleSort(int[] arr) {
for (int i = 1; i < arr.length; i++) { for (int i = 1; i < arr.length; i++) {
// Set a flag, if true, that means the loop has not been swapped, // Set a flag, if true, that means the loop has not been swapped,
// that is, the sequence has been ordered, the sorting has been completed. // that is, the sequence has been ordered, the sorting has been completed.
@ -130,7 +130,7 @@ public static int[] BubbleSort(int[] arr) {
* @param arr * @param arr
* @return arr * @return arr
*/ */
public static int[] SelectionSort(int[] arr) { public static int[] selectionSort(int[] arr) {
for (int i = 0; i < arr.length - 1; i++) { for (int i = 0; i < arr.length - 1; i++) {
int minIndex = i; int minIndex = i;
for (int j = i + 1; j < arr.length; j++) { for (int j = i + 1; j < arr.length; j++) {
@ -184,7 +184,7 @@ public static int[] SelectionSort(int[] arr) {
* @param arr * @param arr
* @return arr * @return arr
*/ */
public static int[] InsertionSort(int[] arr) { public static int[] insertionSort(int[] arr) {
for (int i = 1; i < arr.length; i++) { for (int i = 1; i < arr.length; i++) {
int preIndex = i - 1; int preIndex = i - 1;
int current = arr[i]; int current = arr[i];
@ -234,7 +234,7 @@ public static int[] InsertionSort(int[] arr) {
* @param arr * @param arr
* @return arr * @return arr
*/ */
public static int[] ShellSort(int[] arr) { public static int[] shellSort(int[] arr) {
int n = arr.length; int n = arr.length;
int gap = n / 2; int gap = n / 2;
while (gap > 0) { while (gap > 0) {
@ -291,14 +291,14 @@ public static int[] ShellSort(int[] arr) {
* @param arr * @param arr
* @return arr * @return arr
*/ */
public static int[] MergeSort(int[] arr) { public static int[] mergeSort(int[] arr) {
if (arr.length <= 1) { if (arr.length <= 1) {
return arr; return arr;
} }
int middle = arr.length / 2; int middle = arr.length / 2;
int[] arr_1 = Arrays.copyOfRange(arr, 0, middle); int[] arr_1 = Arrays.copyOfRange(arr, 0, middle);
int[] arr_2 = Arrays.copyOfRange(arr, middle, arr.length); int[] arr_2 = Arrays.copyOfRange(arr, middle, arr.length);
return Merge(MergeSort(arr_1), MergeSort(arr_2)); return merge(mergeSort(arr_1), mergeSort(arr_2));
} }
/** /**
@ -308,7 +308,7 @@ public static int[] MergeSort(int[] arr) {
* @param arr_2 * @param arr_2
* @return sorted_arr * @return sorted_arr
*/ */
public static int[] Merge(int[] arr_1, int[] arr_2) { public static int[] merge(int[] arr_1, int[] arr_2) {
int[] sorted_arr = new int[arr_1.length + arr_2.length]; int[] sorted_arr = new int[arr_1.length + arr_2.length];
int idx = 0, idx_1 = 0, idx_2 = 0; int idx = 0, idx_1 = 0, idx_2 = 0;
while (idx_1 < arr_1.length && idx_2 < arr_2.length) { while (idx_1 < arr_1.length && idx_2 < arr_2.length) {
@ -364,58 +364,32 @@ public static int[] Merge(int[] arr_1, int[] arr_2) {
### 代码实现 ### 代码实现
> 来源：[使用 Java 实现快速排序（详解）](https://segmentfault.com/a/1190000040022056)
```java ```java
/** public static int partition(int[] array, int low, int high) {
* Swap the two elements of an array int pivot = array[high];
* @param array int pointer = low;
* @param i for (int i = low; i < high; i++) {
* @param j if (array[i] <= pivot) {
*/ int temp = array[i];
private static void swap(int[] arr, int i, int j) { array[i] = array[pointer];
int tmp = arr[i]; array[pointer] = temp;
arr[i] = arr[j]; pointer++;
arr[j] = tmp;
} }
System.out.println(Arrays.toString(array));
/**
* Partition function
* @param arr
* @param left
* @param right
* @return small_idx
*/
private static int Partition(int[] arr, int left, int right) {
if (left == right) {
return left;
} }
// random pivot int temp = array[pointer];
int pivot = (int) (left + Math.random() * (right - left + 1)); array[pointer] = array[high];
swap(arr, pivot, right); array[high] = temp;
int small_idx = left; return pointer;
for (int i = small_idx; i < right; i++) {
if (arr[i] < arr[right]) {
swap(arr, i, small_idx);
small_idx++;
} }
public static void quickSort(int[] array, int low, int high) {
if (low < high) {
int position = partition(array, low, high);
quickSort(array, low, position - 1);
quickSort(array, position + 1, high);
} }
swap(arr, small_idx, right);
return small_idx;
}
/**
* Quick sort function
* @param arr
* @param left
* @param right
* @return arr
*/
public static int[] QuickSort(int[] arr, int left, int right) {
if (left < right) {
int pivotIndex = Partition(arr, left, right);
sort(arr, left, pivotIndex - 1);
sort(arr, pivotIndex + 1, right);
}
return arr;
} }
``` ```
@ -493,7 +467,7 @@ private static void heapify(int[] arr, int i) {
* @param arr * @param arr
* @return * @return
*/ */
public static int[] HeapSort(int[] arr) { public static int[] heapSort(int[] arr) {
// index at the end of the heap // index at the end of the heap
heapLen = arr.length; heapLen = arr.length;
// build MaxHeap // build MaxHeap
@ -561,7 +535,7 @@ private static int[] getMinAndMax(int[] arr) {
* @param arr * @param arr
* @return * @return
*/ */
public static int[] CountingSort(int[] arr) { public static int[] countingSort(int[] arr) {
if (arr.length < 2) { if (arr.length < 2) {
return arr; return arr;
} }
@ -640,7 +614,7 @@ private static int[] getMinAndMax(List<Integer> arr) {
* @param arr * @param arr
* @return * @return
*/ */
public static List<Integer> BucketSort(List<Integer> arr, int bucket_size) { public static List<Integer> bucketSort(List<Integer> arr, int bucket_size) {
if (arr.size() < 2 || bucket_size == 0) { if (arr.size() < 2 || bucket_size == 0) {
return arr; return arr;
} }
@ -704,7 +678,7 @@ public static List<Integer> BucketSort(List<Integer> arr, int bucket_size) {
* @param arr * @param arr
* @return * @return
*/ */
public static int[] RadixSort(int[] arr) { public static int[] radixSort(int[] arr) {
if (arr.length < 2) { if (arr.length < 2) {
return arr; return arr;
} }
@ -755,8 +729,6 @@ public static int[] RadixSort(int[] arr) {
## 参考文章 ## 参考文章
https://www.cnblogs.com/guoyaohua/p/8600214.html - https://www.cnblogs.com/guoyaohua/p/8600214.html
- https://en.wikipedia.org/wiki/Sorting_algorithm
https://en.wikipedia.org/wiki/Sorting_algorithm - https://sort.hust.cc/
https://sort.hust.cc/